The present invention relates to a humidity stabilizer, in particular for a musical instrument case.
In particular stringed instruments, and therein especially bowed stringed instruments, react highly sensitively with respect to tone quality to ambient air humidity and its fluctuations. This applies in the case of bowed instruments for the instrument proper as well as also for the bow. For optimum [musical] sound a relative air humidity [r.a.h.] of maximum constancy of 50% to 60% r.a.h. is desired. In particular, in dry zones such as for example in high-altitude valleys of the Alps, in aircraft or also during the winter, the ambient air humidity is customarily not sufficient to ensure optimum [musical] sound quality. In general, in the case of wooden instruments and thus also in the case of woodwind instruments, with too low a relative air humidity or with severe air humidity fluctuations, for example through rapid weather changes or transport of the instrument, mechanical degradation of wood [musical] sound bodies must also be anticipated, such as the development of cracks, in the case of wind instruments their warping to the point of jamming of the valve mechanisms.
It is therefore the goal to maintain in a musical instrument case or trunk an air humidity of 50 to 60% r.a.h. at maximum constancy, largely independently of, in particular, too low an ambient air humidity and of large fluctuations of the ambient air humidity.
From U.S. Pat. No. 3,407,700 a humidity stabilizer is known which, in the form of tubing, comprises a sponge-like core which is moistened through openings in the tubing sheath and through these openings subsequently also gives off moisture. This stabilizer is inserted through the f-shaped holes of bowed instruments into their interior.
This approach is extraordinarily disadvantageous and hardly practical; the danger is given that liquid moisture-retaining substance uncontrollably comes directly into contact with the interior of the instrument which can lead to lasting damage and that, in addition to the degradation of the tone reproduction with stabilizers, as advised, left in the instrument during the playing, the insertion of the stabilizer into the instrument, precisely with bowed instruments, entails the danger of disturbing the sound post with the accompanying known drastic effects caused thereby onto the behavior of the instrument.
Moreover, the stabilizer described in this publication (U.S. Pat. No. 3,407,700) is only capable of maintaining and stabilizing the air humidity in a musical instrument case for approximately two days. This may be one reason why the known stabilizer is inserted into the instrument, namely in order to utilize at least optimally the stabilization effect which, per se, is low.
It is the task of the present invention to eliminate the stated disadvantages of the prior known stabilizers. This is achieved thereby that the air humidity stabilizer according to the invention comprises a stabilizer substance in the form of a hydrophilic water-absorbing polymer.
Preferably as the stabilizer substance is therein used a cross-linked hydrophilic polymer, preferably a polyacrylic acid salt, therein further in particular preferred cross-linked polyacrylic acid sodium salts. This substance can therein be provided xe2x80x94non activatedxe2x80x94in film form or, and today especially preferred, in powder form.
The precise chemical structure of the stabilizer substance used is less important in connection with the present invention; the main point is that the stabilizer substance used according to the invention, such as in particular cross-linked polyacrylic acid sodium salts in powder form, has a pronounced high capability for water absorption. In addition, it is critical that the stabilizer substance used according to the invention absorbs water very rapidly and, while expanding to a multiple of its original volume, forms a gel.
For example, Luquasorb(copyright) AF1 (Luquasorb(copyright) AF1: registered trademark of BASF/Germany) cross-linked polyacrylic acid sodium salt available on the market, which is already used in a number of applications, such as, for example, baby diapers, has in powder form a water absorption capability of up to 40g/100 mg polymer, and 30 g of water are absorbed in approximately 2.5 minutes.
If, as is preferred, the stabilizer substance, provided inactivated and in powder form, is introduced into a container permeable to moisture, preferably into a screen-mesh container, therein in particular preferred comprising a polyamide fabric, i.e. into a polyamide bag which is, for example, at least on one side welded together. The pore size of such a bag, on the one hand for securing maximum moisture circulation, is selected to be large, on the other hand, preferably only of such a size that no liquid or no powder can exude from it. It has been found that a pore size of 70 xcexcm to 120 xcexcm, therein in particular of approximately 90 xcexcm at a thread thickness significantly less than the pore size is optimal.
The air humidity stabilizer according to the invention is, in any event, provided outside of the musical instrument at some site in the case or the trunk of the musical instrument and specifically such that a wet degradation of the instrument or further important pieces sensitive to humidity, such as the bow, is out of the question. The maintenance of a relative air humidity of 50 to 60% r.a.h. is further extremely advantageous, in addition for the instrument including, if appropriate, the bow, also for [colophone] rosin customarily carried in cases for bowed instruments; its capability for bowing is significantly better than when it is completely dried out. If desired, with the present invention it is also possible to maintain with the present invention a different constant air humidity, for example around 30% or around 80% r.a.h.
In order to exclude in any event the wet degradation of the content of the case or trunk of the instrument, it is further suggested to provide a security container such as a hard plastic protective container wherein the substance is accommodated, if appropriate with the moisture-permeable container preferably being exchangeable. On the protective container at least one interior large air inlet opening, which permits the complete ventilation of the substance, potentially through the moisture-permeable container. The stabilizer according to the invention is either integrated directly into the instrument case, in the case of newly manufactured instrument case, or is manufactured and distributed as a component part and, such as for example by means of Velcro tape, fixed in the instrument case.